I have a multitude of arms/cartridges & TT's.
Fyi when I had a hiatus from audio I ran a Shure V15vmr in a modified ET2 - superb results. Also like you I have a Dynavector 501 - the Shure V15vmr sounded very good in that arm as well. The V15 did not sound great with any of my other arms.
So from my point of view you have a great arm/cartridge match with the 501/V15 - I ran the Shure with the stabiliser brush removed.